Gilead leaps ahead with FDA app for PI3K cancer killer

Gilead Sciences ($GILD) has sped ahead of rivals in the race to develop PI3K delta-targeted drugs for treating blood cancer, filing a new drug application with the FDA for its contender called idelalisib. As the biotech giant had said was a possibility, Gilead is seeking an early approval for idelalisib to combat indolent cases of non-Hodgkin's lymphoma (NHL) that fail to respond to rituximab and alkylating-agent chemotherapies.

Foster City, CA-based Gilead, which has a world-leading HIV franchise, has aggressively built a pipeline in oncology in recent years through acquisitions, including its 2011 buyout of Calistoga for up to $600 million, a deal that brought in idelalisib. And early this year Gilead picked up YM Biosciences, a developer of JAK inhibitors, for a tidy $510 million.

Gilead aims to cover new ground with its FDA application. Idelalisib could become the first PI3K delta-targeted drug for a blood cancer and provide a new category of therapy against indolent NHL for the first time in more than 10 years, the company said. While those with indolent NHL classified as follicular lymphoma live a median of 8 to 10 years from diagnosis, refractory or resistant cases offer much worse prospects, according to the company. 

Gilead filed for the approval based on a single-arm Phase II study of idelalisib in 125 patients with iNHL whose cancer was resistant to rituximab and chemo containing alkylating agents. Interim results in June showed that 53.6% of patients on the experimental drug had a response, the median duration of response was 11.9 months, and patients lived a median of 11.4 months without their cancers getting worse. Another sign of efficacy was lymph node shrinkage in 89% of patients.

A minority of patients in the study suffered side effects such as diarrhea (10%), elevated liver enzymes (13%) and neutropenia (26%).

The FDA app follows the start of late-stage development of idelalisib in combination with other therapies for indolent NHL as well as chronic lymphocytic leukemia (CLL), one of the most common blood cancers. The orally taken compound has drawn comparisons to Infinity Pharmaceuticals' ($INFI) lead candidate IPI-145, an inhibitor of PI3K delta and gamma signaling, which has begun midstage development in indolent NHL. Gilead clearly has the lead in the PI3K delta contest.

Gilead's and Infinity's drugs are designed to block overactive PI3K (phosphoinositide 3-kinase) delta signaling, smothering one of the key drivers of cancer growth in B-cell leukemias and lymphomas.

Yet the company faces major competition in the CLL arena, where Pharmacylics ($PCYC) and partner Johnson & Johnson's ($JNJ) BTK inhibitor ibrutinib has taken an inside track toward FDA approval for the cancers. Also, Roche/Genentech is seeking the agency's nod for its next-gen version of rituximab called GA101 in CLL. Both ibrutinib and GA101 have garnered breakthrough therapy status from the FDA.

- here's Gilead's release

Special Report: Top 10 experimental cancer drugs - 2013 - Idelalisib